Thanks sugarcatmom, you have been wonderful.
The symptoms she had was her hair falling out and throwing up. The science diet did help a bit and it was what our vet recommended, but I will look into other types of food for her.
I should also clarify that I said this has been going on for about six months and that was an estimate with some room to wiggle. It was a gradual process with the food problems until it got to this point and it seemed like suddenly something was really wrong! We love our cats and will do anything to keep them healthy. I never like correcting them in any way, so this is a huge relief to know that she can't help it. Now I feel like such a jerk